add highcon demo #181

doc/man/man1/notcurses-demo.1.md

@@ -27,6 +27,7 @@ The demonstrations include (see NOTES below):
 * (e)agle—they took some time off my life, back in the day
 * (f)allin'—the screen falls apart under heavy blows
 * (g)rid—a gradient of color lain atop a great grid
+* (h)ighcon—high contrast text atop various colors
 * (j)ungle—low-bandwidth color cycling reveals ancient ruins
 * (l)uigi-a dashing Apennine plumber in a world of fire
 * (r)eel—demonstration of the ncreel high-level widget
@@ -62,7 +63,7 @@ At any time, press 'q' to quit. The demo is best run in at least a 80x45 termina
 
 **-V**: Print the program name and version, and exit with success.
 
-demospec: Select which demos to run, and what order to run them in. The default is **ixetbcgrwuvlfsjo**. See above for a list of demos.
+demospec: Select which demos to run, and what order to run them in. The default is **ixethbcgrwuvlfsjo**. See above for a list of demos.
 
 # NOTES
 

src/demo/demo.c

@@ -22,12 +22,12 @@ static char datadir[PATH_MAX];
 static atomic_bool interrupted = ATOMIC_VAR_INIT(false);
 
 #ifdef DISABLE_FFMPEG
-static const char DEFAULT_DEMO[] = "itbgrwus";
+static const char DEFAULT_DEMO[] = "ithbgrwus";
 #else
 #ifdef DFSG_BUILD
-static const char DEFAULT_DEMO[] = "ixtbgrwuso";
+static const char DEFAULT_DEMO[] = "ixthbgrwuso";
 #else
-static const char DEFAULT_DEMO[] = "ixetbcgrwuvlfsjo";
+static const char DEFAULT_DEMO[] = "ixethbcgrwuvlfsjo";
 #endif
 #endif
 
@@ -105,7 +105,7 @@ static struct {
   NONFREE("eagle", eagle_demo),
   NONFREE("fallin'", fallin_demo),
   { "grid", grid_demo, },
-  { NULL, NULL, },
+  { "highcon", highcontrast_demo, },
   { "intro", intro, },
   NONFREE("jungle", jungle_demo),
   { NULL, NULL, },

src/demo/demo.h

@@ -34,6 +34,7 @@ int trans_demo(struct notcurses* nc);
 int chunli_demo(struct notcurses* nc);
 int grid_demo(struct notcurses* nc);
 int fallin_demo(struct notcurses* nc);
+int highcontrast_demo(struct notcurses* nc);
 int jungle_demo(struct notcurses* nc);
 int sliding_puzzle_demo(struct notcurses* nc);
 int view_demo(struct notcurses* nc);

src/demo/highcon.c

@@ -0,0 +1,62 @@
+#include "demo.h"
+
+// Derive the next color based on current state. *'total' ranges from 0 to 768
+// in steps of 4. We increment it upon exhaustion of component colors summing
+// to that value. While the 'r', 'g', and 'b', components range from 0 to 256,
+// the return value caps each component at 255.
+static unsigned
+generate_next_color(unsigned *total, unsigned *r, unsigned *g, unsigned *b){
+}
+
+int highcontrast_demo(struct notcurses* nc){
+  int dimy, dimx;
+  struct ncplane* n = notcurses_stdplane(nc);
+  ncplane_dim_yx(n, &dimy, &dimx);
+  int totcells = dimy * dimx;
+  unsigned iteration = 0;
+  // circular array of current background colors, starting logically at
+  // iteration % totcells.
+  unsigned* scrcolors = malloc(sizeof(*scrcolors) * totcells);
+  if(scrcolors == NULL){
+    return -1;
+  }
+  // build up the initial screen
+  do{
+  }while(iterations < totcells);
+  // we want to fill one screen (totcells) with a broad spectrum of color. rgb
+  // can have between 0 and 765 total component units (0/0/0 vs 255/255/255).
+  // each of those totals can result in 1 color. the total 384 will maximize 
+  // the number of colors, with 200 at intervals of 16. at 512+, all components
+  // must be positive; at 254-, no components can be maximized. at intervals of
+  // 4, we have ~5M colors between 0..765.
+  unsigned total, r, g, b;
+  total = r = g = b = 0;
+  unsigned rgb;
+  // each iteration, generate the next color, and introduce it at the lower
+  // right. start at the upper left, from the logical beginning of the array.
+  cell c = CELL_SIMPLE_INITIALIZER(' ');
+  do{
+    int idx = iterations % totcells; // first color for upper-left
+    for(int y = 0 ; y < dimy ; ++y){
+      for(int x = 0 ; x < dimx ; ++x){
+        cell_set_fg();
+        if(ncplane_putc_yx(n, y, x, &c) < 0){
+          goto err;
+        }
+      }
+    }
+    rgb = generate_next_color(&total, &r, &g, &b);
+    if(notcurses_render(nc)){
+      goto err;
+    }
+  }while(rgb < 0xffffff);
+  // FIXME fill screen with a matrix of text, all high-contrast
+  // FIXME cycle the background matrix
+  free(scrcolors);
+  return 0;
+
+err:
+  release_cell(n, &c);
+  free(scrcolors);
+  return -1;
+}